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    <script>
        // 2、求出1-1/2 + 1/3 - 1/4 + 1/5....... 1/100的和
        var sum = 0;
        for (i = 1; i <= 100; i++) {
            if (i % 2 !== 0) {
                sum = sum + 1 / i
            } else if (i % 2 === 0) {
                sum = sum - 1 / i
            }
        }
        console.log(sum)
    </script>
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